When rotating or scaling groups of objects, have option to snap centroid to grid

I find that I use Blender's grid snapping features when I'm blocking in levels, and it helps a great deal in keeping things organized. However, I find that I'll often select a group of objects and then either rotate or scale them and the result is usually not aligned to the grid. I think this is because these operations rotate and scale around the averaged center of the selected objects rather than a grid aligned point.

I'd like to suggest that either the tools should have an option added so that they work with respect to the grid or maybe have this snapping behavior automatically used whenever snap mode is enabled.